The execution-style slaying a 10-year-old boy and the girlfriend of the boy's father have been linked to what was supposed to have been a small marijuana transaction - a routine bit of business that the father conducted out of his Alief townhouse and which often involved his two sons, according to a prosecutor's affidavit.

Instead, the purported drug buyers shot and killed Brandon Vu and Le Nguyen, 41, and left Hoai Vu for dead, also with a gunshot to the head. Hoai Vu, the alleged dealer, remains in a coma in Memorial Hermann Hospital. The assailants netted 7 pounds of marijuana and $20,000 in cash, according to the affidavit.

Details of the drug deal-turned-deadly shooting were provided to police by one of the four men who have been arrested and charged with capital murder in connection with the May 13 killings.

Bobby Austin, 23, told Houston police he was paid $500 to drive.

He drove the other three to the townhouse in the 6600 block of Westwick and then quickly sped away, returning minutes later to pick them up after the killings. Their comings and goings were captured by nearby surveillance cameras.

Hoai Vu, 40, typically took calls from would-be drug buyers on a special cell phone, his 14-year-old son, Justin Vu, told police. After a deal was arranged, the buyer would drive up to the townhome and be let in through the garage by one of Vu's sons, who would then take the buyer upstairs to complete the deal. Justin Vu discovered the killings minutes after they occurred.

Besides the surveillance video, police were able to connect the four to Hoai Vu through cell phone records. Though his "drug" phone was stolen during the robbery, phone records showed a handful of calls made to his number from a cell phone in the possession of Godine.

Austin told police that as the group made its getaway, Godine told him he had shot the three, according to the affidavit.

Godine then allegedly made calls to try to find someone to burn down the Vus' home to destroy evidence of the crime.